A single missing or misdirected nozzle can result in unacceptable image quality in single-pass printing applications (see FIG. 2A). Without compensating for these poorly performing nozzles, waste and scrap is incurred.
Preventative and reactive maintenance can be used to compensate for poorly performing nozzles. For example, cleaning the print head can often recover failed nozzles. However, even with automated cleaning stations, this approach requires that the press be shut down for at least a short period of time. After the cleaning, the operator must check the nozzles to see if the cleaning was effective. Additionally, while preventative maintenance, e.g. performing periodic regular cleaning in the hope of avoiding a failed nozzle, can help it is not a foolproof system because nozzles can fail unpredictably from a variety of causes.
Redundant nozzles can be used to compensate for poorly performing nozzles. If nozzles are paired so that two or more nozzles print the same color on roughly the same raster column, the image duty is divided between these nozzles. If one of these nozzles fails, the impact on the print is significantly less than if a single nozzle was used to print that part of the image. However, this approach significantly increases the cost and complexity of the printer.
Color replacement can be used to compensate for poorly performing nozzles. In this approach, other colors are used to fill in for the missing nozzle, Thus, a mixture of cyan, magenta, and yellow could compensate for a missing black nozzle. However, this technique suffers when a colorimetric match requires the use of a color profile because the image must be re-ripped in real time. Likewise, there could be primary colors, e.g. yellow, that have no other color capable of filling in.
It would be advantageous to provide a technique that compensates for missing or misdirected nozzles that otherwise would result in unacceptable image quality in single-pass printing applications.